1. Field of the Invention
The present invention relates to thin laminate structures comprising a film layer of metalized resin, which laminate structure is to be exposed in use to extremes in weather environment. It is particularly concerned with such laminates employed in protective and decorative trim molding strips applied to doors and side panels of automobile bodies and to edges of automobile doors.
2. Prior Art
Within about the past decade, metal molding strips employed as decorative or protective ("rub-rails") trim on the doors and side panels of automobiles have been largely replaced by plastic extrusions. Typical extruded moldings and edgings for application to the sides of automobiles and to the edges of the doors respectively are well known in the art as shown for example in the U.S. Pat. Nos. 3,440,129; 3,494,075; 3,531,348; 3,681,180; 3,687,502; 3,881,042; 3,914,482; 3,922,460; 3,970,498; 3,982,780; 4,010,927. Certain of the listed patents, among others, disclose plastic extrusions provided with a laminated layer comprising a metalized or metal-coated resin film. The typical structure widely employed for such application is formed of a three-ply laminate which generally is comprised of an aluminized polyester (such as aluminized "Mylar") film of about 0.5 mil thickness, adhesively bonded to an outer polyvinyl fluoride protective film of about 1 mil thickness. The opposite side of the metalized polyester film is adhesively bonded to a base layer of a virgin vinyl resin. This tri-laminate is applied to a running length of the extruded molding strip generally comprised of a virgin vinyl resin. The tri-laminate may be heat fused to the extruded strip or may be further provided with a backing of suitable adhesive to enhance or facilitate bonding to the resin extrusion. One form of such tri-laminate is disclosed in the U.S. Pat. No. 3,982,780, Example 2.
While tri-laminates of the type above described are widely used commercially, these as well as other proposed laminate structures have been found to present frequent problems, particularly from the standpoint of peeling or delamination. Such delamination tendency is at times already observed on standard testing of samples of the laminate or of the finished extrusion strip to which the laminate is applied, when the sample is subjected to prescribed weather environment conditions for indicated time periods. Even such products that are deemed acceptable in having successfully passed the prescribed tests, are in many instances later found defective and subject to subsequent complaints by automobile users and dealers. Such loss of bonding of the laminated molding strip often results from seepage of water between layers of the laminate, particularly between the metalized surface and the next adjacent layer. Apparently, the contained water penetrating the laminate is caused to evaporate when exposed to the sun's radiant heat and thus tends to break the bond between the strata. In other instances breaks in the continuity of the surface film of the molding strip as a result of impact or scratching, expose areas at which delamination may be initiated.
Among the objects of the present invention, therefore, are to provide an improved laminate structure comprising a metalized resin film layer, designed to overcome or largely mitigate the problems hitherto encountered in the use of such laminates.